In the traditional public switched telephone network (PSTN), the addition of a new service frequently required the upgrading of switching equipment and software. This was frequently an expensive and complex process. As new telecommunication services were developed and became widely available, the need to reduce the overhead for using services increased, along with the need to simplify maintenance and service upgrades. These needs led to the development of the Intelligent Network (IN) concept.
The IN concept provided a centralized system that separated services from switching equipment. Thus, a provider may introduce a new service without performing a major modification on multiple switches. In an IN architecture, separate service data is stored in a centralized database outside of switching nodes. An IN architecture also separates service programs (or service logic) and defines protocols that permit the interaction between switching systems and intelligent nodes.
FIG. 2 illustrates telecommunication switch 200, which is part of a conventional Intelligent Network (IN) architecture according to an exemplary embodiment of the prior art. In particular, FIG. 2 illustrates an intelligent network (IN) switch model that may be implemented as a mobile switching center (MSC) commonly found in many wireless networks. In this example, switch 200 is a service switching point (SSP) that complies with the International Telecommunication Union—Telecommunications (ITU-T) Capability Set 1 (CS-1) architecture.
For ease of explanation, switch 200 comprises originating side 202a and terminating side 202b. Originating side 202a represents the side of switch 200 that faces the component originating a call and terminating side 202b represents the other side of switch 200. In general, originating side 202a receives and processes a signaling message. Once processing is complete, a function in terminating side 202b is selected and call processing is performed to terminate the call, such as to a trunk line. Depending on which component originates a call, originating side 202a and terminating side 202b of switch 200 may be reversed.
According to the embodiment in FIG. 2, switch 200 comprises two call control functions (CCFs) 204a-204b. Call control functions 204a-204b are responsible for establishing, maintaining, modifying, and releasing telephone calls routed through switch 200. For example, call control function 204a may receive a signaling message indicating that a telephone call is being placed, and call control function 204b facilitates the establishment of a circuit with another component in the system. Call control functions 204a-204b also monitor the overall state of telephone calls routed through switch 200. In addition, call control functions 204a-204b detect particular triggers associated with a telephone call, such as a trigger representing the invocation of a particular feature (e.g., Hold) or a busy signal.
In addition, switch 200 comprises service switching functions (SSFs) 208a-208b. Service switching functions 208a-208b allow switch 200 to interact and communicate with one or more service control functions, such as service control function (SCF) 210, located in service control points (SCPs). For example, when call control functions 204a-204b detect triggers associated with telephone calls, call control functions 204a-204b pass the triggers to service switching functions 208a-208b. Service switching functions 208a-208b then allow switch 200 to pass the triggers to one of the service control points and access the service control function of that service control point. Service control function 210 executes logic for various intelligent network services and may influence the call processing performed by switch 200.
Service control function 210 may interact with service data function (SDF) 212 and specialized resource function (SRF) 214. Service data function 212 provides data to service control function 210, such as data related to customers. For one embodiment, service data function 212 comprises the functionality of a service data point (SDP). Specialized resource function 214 provides additional functionality, such as speech analysis or conference calling functions. In an exemplary embodiment, specialized resource function 214 may comprise the functionality of an intelligent peripheral.
Call control functions 204a and 204b may be accessed using generic application programming interfaces (APIs). Call control functions 204a and 204b receive service requests from, and transmit service responses to, external devices, such as mobile stations (via the base stations of a wireless network). In general, call control functions 204a and 204b transmit and receive signaling control primitives, which may vary from one signaling protocol to another.
The current state of IN development is Capability Set 2 (CS-2). CS-2 enables interworking between IN architectures to provide international services, allows management of both IN services and IN equipment, and supports enhanced IN services, such as mobility services. As in a CS-1 switch, all service requests received in a CS-2 based IN switch are sent to an external application for processing. There are numerous disadvantages to this approach. First, all messages must be encoded and decoded using the Intelligent Network Application Protocol (INAP). Also, all service requests must be transferred as external messages between the switching device and the local SCF. Furthermore, only CS-2 specified subscriber data may be sent to the local SCF. All other subscriber data must be specially formatted or encoded. This makes it difficult to add proprietary information in order to customize services.
Therefore, there is a need in the art for an improved Intelligent Network (IN) switch. In particular, there is a need for a CS-2-based IN switch that performs at least some services in the core network and does not required the use of an external application, such as a service control function (SCF). More particularly, there is a need for a CS-2-based IN switch that transfers messages related to a service request without INAP encoding and decoding.